Enforce filter length validation and add tests for Shard plugin (#1673)

src/Plugins/Shard.php

@@ -27,6 +27,13 @@ final class Shard implements AddsOutput, HandlesArguments, Terminable
 
     private const string SHARD_OPTION = 'shard';
 
+    /**
+     * The maximum length allowed for the filter argument.
+     * While ARG_MAX can be 2MB, individual arguments are often limited to 128KB (MAX_ARG_STRLEN).
+     * Practical limits in CI environments (like Docker or pipeline runners) can be even lower.
+     */
+    private const int MAX_FILTER_LENGTH = 32768;
+
     /**
      * The shard index and total number of shards.
      *
@@ -146,7 +153,11 @@ final class Shard implements AddsOutput, HandlesArguments, Terminable
             return $arguments;
         }
 
-        return [...$arguments, '--filter', $this->buildFilterArgument($testsToRun)];
+        $filter = $this->buildFilterArgument($testsToRun);
+
+        $this->ensureFilterLengthIsSafe($filter);
+
+        return [...$arguments, '--filter', $filter];
     }
 
     /**
@@ -209,12 +220,34 @@ final class Shard implements AddsOutput, HandlesArguments, Terminable
 
     /**
      * Builds the filter argument for the given tests to run.
+     *
+     * @param  array<int, string>  $testsToRun
      */
-    private function buildFilterArgument(mixed $testsToRun): string
+    private function buildFilterArgument(array $testsToRun): string
     {
         return addslashes(implode('|', $testsToRun));
     }
 
+    /**
+     * Ensures that the filter length is safe for the current environment.
+     *
+     * @throws InvalidOption
+     */
+    private function ensureFilterLengthIsSafe(string $filter): void
+    {
+        $maxLength = (int) (getenv('PEST_SHARD_MAX_FILTER_LENGTH') ?: self::MAX_FILTER_LENGTH);
+
+        if (strlen($filter) > $maxLength) {
+            throw new InvalidOption(sprintf(
+                'The generated filter for this shard is too long (%d characters). '.
+                'This can cause issues with some environments (limit is %d characters). '.
+                'Please increase the number of shards (e.g., use 1/4 instead of 1/2) to reduce the filter length.',
+                strlen($filter),
+                $maxLength
+            ));
+        }
+    }
+
     /**
      * Adds output after the Test Suite execution.
      */

tests/Unit/Plugins/Shard.php

@@ -0,0 +1,209 @@
+<?php
+
+use Pest\Exceptions\InvalidOption;
+use Pest\Plugins\Shard;
+use Symfony\Component\Console\Input\ArgvInput;
+use Symfony\Component\Console\Output\BufferedOutput;
+
+describe('getShard', function () {
+    it('parses valid shard format', function (string $format, int $expectedIndex, int $expectedTotal) {
+        $input = new ArgvInput(['test', '--shard', $format]);
+
+        $result = Shard::getShard($input);
+
+        expect($result)->toBe([
+            'index' => $expectedIndex,
+            'total' => $expectedTotal,
+        ]);
+    })->with([
+        ['1/2', 1, 2],
+        ['2/2', 2, 2],
+        ['1/4', 1, 4],
+        ['4/4', 4, 4],
+        ['1/10', 1, 10],
+        ['10/10', 10, 10],
+        ['5/100', 5, 100],
+    ]);
+
+    it('throws exception for invalid format', function (array $arguments) {
+        $input = new ArgvInput($arguments);
+
+        Shard::getShard($input);
+    })->with([
+        [['test', '--shard', 'invalid']],
+        [['test', '--shard', '1']],
+        [['test', '--shard', '1/']],
+        [['test', '--shard', '/2']],
+        [['test', '--shard', 'a/b']],
+        [['test', '--shard', '1.5/2']],
+    ])->throws(InvalidOption::class);
+
+    it('throws exception for invalid index or total values', function (array $arguments) {
+        $input = new ArgvInput($arguments);
+
+        Shard::getShard($input);
+    })->with([
+        [['test', '--shard', '0/2']],
+        [['test', '--shard', '1/0']],
+        [['test', '--shard', '3/2']],
+        [['test', '--shard', '5/4']],
+    ])->throws(InvalidOption::class);
+});
+
+describe('ensureFilterLengthIsSafe', function () {
+    it('accepts filter within length limit', function () {
+        $output = new BufferedOutput;
+        $shard = new Shard($output);
+
+        $reflection = new ReflectionClass($shard);
+        $method = $reflection->getMethod('ensureFilterLengthIsSafe');
+
+        $filter = str_repeat('a', 1000);
+
+        $method->invoke($shard, $filter);
+
+        expect(true)->toBeTrue();
+    });
+
+    it('throws exception when filter exceeds default limit', function () {
+        $output = new BufferedOutput;
+        $shard = new Shard($output);
+
+        $reflection = new ReflectionClass($shard);
+        $method = $reflection->getMethod('ensureFilterLengthIsSafe');
+
+        $filter = str_repeat('a', 32769);
+
+        $method->invoke($shard, $filter);
+    })->throws(InvalidOption::class, 'The generated filter for this shard is too long');
+
+    it('respects custom limit from environment variable', function () {
+        putenv('PEST_SHARD_MAX_FILTER_LENGTH=1000');
+
+        $output = new BufferedOutput;
+        $shard = new Shard($output);
+
+        $reflection = new ReflectionClass($shard);
+        $method = $reflection->getMethod('ensureFilterLengthIsSafe');
+
+        $filter = str_repeat('a', 1001);
+
+        try {
+            $method->invoke($shard, $filter);
+            expect(false)->toBeTrue('Should have thrown exception');
+        } catch (InvalidOption $e) {
+            expect($e->getMessage())->toContain('1001 characters')
+                ->and($e->getMessage())->toContain('limit is 1000 characters');
+        } finally {
+            putenv('PEST_SHARD_MAX_FILTER_LENGTH');
+        }
+    });
+
+    it('accepts filter within custom limit', function () {
+        putenv('PEST_SHARD_MAX_FILTER_LENGTH=1000');
+
+        $output = new BufferedOutput;
+        $shard = new Shard($output);
+
+        $reflection = new ReflectionClass($shard);
+        $method = $reflection->getMethod('ensureFilterLengthIsSafe');
+
+        $filter = str_repeat('a', 999);
+
+        try {
+            $method->invoke($shard, $filter);
+            expect(true)->toBeTrue();
+        } catch (InvalidOption) {
+            expect(false)->toBeTrue('Should not have thrown exception');
+        } finally {
+            putenv('PEST_SHARD_MAX_FILTER_LENGTH');
+        }
+    });
+});
+
+describe('handleArguments', function () {
+    it('returns original arguments when shard option is not present', function () {
+        $output = new BufferedOutput;
+        $shard = new Shard($output);
+
+        $arguments = ['bin/pest', 'tests/', '--parallel'];
+
+        $result = $shard->handleArguments($arguments);
+
+        expect($result)->toBe($arguments);
+    });
+
+    it('removes parallel arguments from test discovery', function () {
+        $output = new BufferedOutput;
+        $shard = new Shard($output);
+
+        $reflection = new ReflectionClass($shard);
+        $method = $reflection->getMethod('removeParallelArguments');
+
+        $arguments = ['bin/pest', '--parallel', 'tests/', '-p'];
+
+        $result = $method->invoke($shard, $arguments);
+
+        expect($result)->toBe([0 => 'bin/pest', 2 => 'tests/']);
+    });
+});
+
+describe('addOutput', function () {
+    it('displays shard information after test execution', function () {
+        $output = new BufferedOutput;
+        $shard = new Shard($output);
+
+        $reflection = new ReflectionClass($shard);
+        $property = $reflection->getProperty('shard');
+        $property->setValue(null, [
+            'index' => 2,
+            'total' => 4,
+            'testsRan' => 25,
+            'testsCount' => 100,
+        ]);
+
+        $exitCode = $shard->addOutput(0);
+        $outputText = $output->fetch();
+
+        expect($exitCode)->toBe(0)
+            ->and($outputText)->toContain('Shard:')
+            ->and($outputText)->toContain('2 of 4')
+            ->and($outputText)->toContain('25 files ran')
+            ->and($outputText)->toContain('out of 100');
+    });
+
+    it('uses singular form for single test file', function () {
+        $output = new BufferedOutput;
+        $shard = new Shard($output);
+
+        $reflection = new ReflectionClass($shard);
+        $property = $reflection->getProperty('shard');
+        $property->setValue(null, [
+            'index' => 1,
+            'total' => 4,
+            'testsRan' => 1,
+            'testsCount' => 100,
+        ]);
+
+        $shard->addOutput(0);
+        $outputText = $output->fetch();
+
+        expect($outputText)->toContain('1 file ran')
+            ->and($outputText)->not->toContain('1 files');
+    });
+
+    it('returns original exit code when shard is not set', function () {
+        $output = new BufferedOutput;
+        $shard = new Shard($output);
+
+        $reflection = new ReflectionClass($shard);
+        $property = $reflection->getProperty('shard');
+        $property->setValue(null, null);
+
+        $exitCode = $shard->addOutput(1);
+        $outputText = $output->fetch();
+
+        expect($exitCode)->toBe(1)
+            ->and($outputText)->not->toContain('Shard:');
+    });
+});